/*
 * Copyright (C) 2011, 2015-2016 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#pragma once

#include "BytecodeConventions.h"
#include "include/JavaScriptCore/interpreter/CallFrame.h"
#include <wtf/PrintStream.h>

namespace JSC {

    inline bool operandIsLocal(int operand) {
        return operand < 0;
    }

    inline bool operandIsArgument(int operand) {
        return operand >= 0;
    }


    class VirtualRegister {
    public:
        friend VirtualRegister virtualRegisterForLocal(int);

        friend VirtualRegister virtualRegisterForArgument(int, int);

        VirtualRegister()
                : m_virtualRegister(s_invalidVirtualRegister) {}

        explicit VirtualRegister(int virtualRegister)
                : m_virtualRegister(virtualRegister) {}

        bool isValid() const { return (m_virtualRegister != s_invalidVirtualRegister); }

        bool isLocal() const { return operandIsLocal(m_virtualRegister); }

        bool isArgument() const { return operandIsArgument(m_virtualRegister); }

        bool isHeader() const { return m_virtualRegister >= 0 && m_virtualRegister < CallFrameSlot::thisArgument; }

        bool isConstant() const { return m_virtualRegister >= s_firstConstantRegisterIndex; }

        int toLocal() const {
            ASSERT(isLocal());
            return operandToLocal(m_virtualRegister);
        }

        int toArgument() const {
            ASSERT(isArgument());
            return operandToArgument(m_virtualRegister);
        }

        int toConstantIndex() const {
            ASSERT(isConstant());
            return m_virtualRegister - s_firstConstantRegisterIndex;
        }

        int offset() const { return m_virtualRegister; }

        int offsetInBytes() const { return m_virtualRegister * sizeof(Register); }

        bool operator==(VirtualRegister other) const { return m_virtualRegister == other.m_virtualRegister; }

        bool operator!=(VirtualRegister other) const { return m_virtualRegister != other.m_virtualRegister; }

        bool operator<(VirtualRegister other) const { return m_virtualRegister < other.m_virtualRegister; }

        bool operator>(VirtualRegister other) const { return m_virtualRegister > other.m_virtualRegister; }

        bool operator<=(VirtualRegister other) const { return m_virtualRegister <= other.m_virtualRegister; }

        bool operator>=(VirtualRegister other) const { return m_virtualRegister >= other.m_virtualRegister; }

        VirtualRegister operator+(int value) const {
            return VirtualRegister(offset() + value);
        }

        VirtualRegister operator-(int value) const {
            return VirtualRegister(offset() - value);
        }

        VirtualRegister operator+(VirtualRegister value) const {
            return VirtualRegister(offset() + value.offset());
        }

        VirtualRegister operator-(VirtualRegister value) const {
            return VirtualRegister(offset() - value.offset());
        }

        VirtualRegister &operator+=(int value) {
            return *this = *this + value;
        }

        VirtualRegister &operator-=(int value) {
            return *this = *this - value;
        }

        void dump(PrintStream &out) const;

    private:
        static const int s_invalidVirtualRegister = 0x3fffffff;
        static const int s_firstConstantRegisterIndex = FirstConstantRegisterIndex;

        static int localToOperand(int local) { return -1 - local; }

        static int operandToLocal(int operand) { return -1 - operand; }

        static int operandToArgument(int operand) { return operand - CallFrame::thisArgumentOffset(); }

        static int argumentToOperand(int argument) { return argument + CallFrame::thisArgumentOffset(); }

        int m_virtualRegister;
    };

    COMPILE_ASSERT(sizeof(VirtualRegister) == sizeof(int), VirtualRegister_is_32bit);

    inline VirtualRegister virtualRegisterForLocal(int local) {
        return VirtualRegister(VirtualRegister::localToOperand(local));
    }

    inline VirtualRegister virtualRegisterForArgument(int argument, int offset = 0) {
        return VirtualRegister(VirtualRegister::argumentToOperand(argument) + offset);
    }

} // namespace JSC
